Ancestry.com couldn't locate records showing when Mitt Romney's parents and grandparents returned to the United States to live.... [Link]

Before you get alarmed, let me assure you that I have already notified the Department of Homeland Security about this situation, and that proceedings are underway to deport Mr. Romney and his fence-jumping family back to Chihuahua.

President Bush has weighed in on the issue, saying that if Congress would promptly institute his guest-worker program, the Romneys could stay in this country and do the jobs that Americans don't want to do—like picking lettuce and talking to Bill O'Reilly.

But, according to Wikipedia, "The phrase "natural born citizen", although it appears in the documents, is not defined anywhere in the Constitution itself and its interpretation has never been the subject of a U.S. Supreme Court ruling. Nevertheless, most United States citizens are assumed to be natural-born citizens, which is thought to mean they have been citizens since birth by virtue of having been born in the United States or born to a United States citizen (or citizens) outside of a U.S. state."

Since both of Mitt's grandparents were born in Utah, and US Citizens, their son, Mitt's father, would me a US Citizen born outside of the US.